/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.iotdb.db.queryengine.plan.relational.metadata;

/**
 * Represents a handle to a column within a {@link TableHandle} returned from the connector to the
 * engine. It will be used by the engine whenever given column will be accessed.
 *
 * <p>ColumnHandle should follow:
 *
 * <ul>
 *   <li>a table cannot have two equal column handles
 *   <li>column handle is unique within a table scope. Two different tables can have two equal
 *       column handles
 * </ul>
 */
public interface ColumnHandle {
  @Override
  int hashCode();

  @Override
  boolean equals(Object other);
}
